vendredi 24 février 2017

(Highlights: Week of Feb. 13, 2017) - It was harvest week for another crop of vegetables on the International Space Station.

NASA astronaut Peggy Whitson photographed and harvested Tokyo Bekana cabbage – also known as Chinese cabbage – capping another round of the Veg-03 investigation. Understanding how plants respond to microgravity is an important step for future long-duration space missions, which will require crew members to grow their own food. Astronauts on the station have previously grown lettuce and flowers in the Veggie facility. This new series of the study expanded on previous validation tests. Whitson froze some of the crop for return to Earth, and set aside some for mealtime with the crew before cleaning and drying the facility.

Veggie provides lighting and necessary nutrients for plants by using a low-cost growth chamber and planting pillows, which deliver nutrients to the root system. The Veggie pillow concept is a low-maintenance, modular system that requires no additional energy beyond a special light to help the plants grow. It supports a variety of plant species that can be cultivated for fresh food, and even for education experiments.

Image above: NASA astronaut Shane Kimbrough works on the Capillary Flow Experiment on the space station. This study examines how liquid flows in space and could improve the reliability of water purification, fuels storage and supply, and general liquid transport on spacecraft. Image Credit: NASA.

Crew members have commented that they enjoy space gardening, and investigators believe growing plants could provide a psychological benefit to crew members on long-duration missions, just as gardening is often an enjoyable hobby for people on Earth. Data from this investigation could benefit agricultural practices on Earth by designing systems that use valuable resources such as water more efficiently.

ESA (European Space Agency) astronaut Thomas Pesquet completed over 15 test runs for the final operations of the Capillary Flow Experiment (CFE-2), working with the ground team to collect important data for new mathematical models of liquid flow types. Liquids behave differently in space than they do on Earth, so containers that can process, hold or transport them must be designed carefully to work in microgravity. The Capillary Flow Experiment furthers research on wetting, which is a liquid’s ability to spread across a surface. The study demonstrates how capillary forces work in space, how differently shaped containers change the wicking behavior of a wetting fluid, and how such can be used to passively separate liquids and gases. Understanding how microgravity amplifies these behaviors could improve the reliability of such key processes as water purification, fuel storage and supply, and general liquid transport aboard spacecraft.

On Earth, capillary action allows small amounts of liquid to flow up and into tight spaces despite the effects of gravity. New miniature medical devices, known as lab-on-a-chip technologies, exploit this phenomenon to draw blood or other fluids into essentially miniature diagnostic systems. CFE-2 improves our understanding of how capillary forces work in a variety of system geometries including the open spaces within porous materials such as sand and soil, wicks and sponges.

NASA astronaut Shane Kimbrough moved the Simple Solar Neutron Detector from the U.S. Lab to Node 1, continuing the study of solar radiation on the space station. Like any star, our sun gives off neutron radiation. The physical properties of neutrons, in particular the absence of electric charge, presents significant challenges to their detection. Astronauts are particularly sensitive to low-energy neutron exposure, which has adverse health consequences, and can cause materials fatigue and degradation issues if spacecraft components are exposed to solar neutrons over long periods.

This investigation from the University of Nebraska in Lincoln involves a new type of detector on the station to measure solar neutrons of lower energy. In addition to confirming decades-long predictions that the sun generates neutrons, the project investigates radiation damage and materials fatigue associated with these neutrons. A space-based approach is essential to this task, since ground-based neutron detectors are subject to interference as interactions of energetic particles with the atmosphere create secondary, non-solar neutrons.

These images show two such objects that Cassini originally detected in spring 2016, as the spacecraft transitioned from more equatorial orbits to orbits at increasingly high inclination about the planet's equator.

Imaging team members studying these objects gave them the informal designations F16QA (right image) and F16QB (left image). The researchers have observed that objects such as these occasionally crash through the F ring's bright core, producing spectacular collisional structures (see PIA08863), similar to those created in 2006 and 2007 by the object designated S/2004 S 6 (see PIA07716).

While these objects may be mostly loose agglomerations of tiny ring particles, scientists suspect that small, fairly solid bodies lurk within each object, given that they have survived several collisions with the ring since their discovery. The faint retinue of dust around them is likely the result of the most recent collision each underwent before these images were obtained.

The researchers think these objects originally form as loose clumps in the F ring core as a result of perturbations triggered by Saturn's moon Prometheus (see PIA08397 and PIA08947). If they survive subsequent encounters with Prometheus, their orbits can evolve, eventually leading to core-crossing clumps that produce spectacular features, even though they collide with the ring at low speeds.

The images were obtained using the Cassini spacecraft narrow-angle camera on Feb. 5, 2017, at a distance of 610,000 miles (982,000 kilometers, left image) and 556,000 miles (894,000 kilometers, right image) from the F ring. Image scale is about 4 miles (6 kilometers) per pixel.

The Cassini mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.

NASA’s Juno spacecraft skimmed the upper wisps of Jupiter’s atmosphere when JunoCam snapped this image on Feb. 2 at 5:13 a.m. PT (8:13 a.m. ET), from an altitude of about 9,000 miles (14,500 kilometers) above the giant planet’s swirling cloudtops.

Streams of clouds spin off a rotating oval-shaped cloud system in the Jovian southern hemisphere. Citizen scientist Roman Tkachenko reconstructed the color and cropped the image to draw viewers’ eyes to the storm and the turbulence around it.

Three decades ago, astronomers spotted one of the brightest exploding stars in more than 400 years. The titanic supernova, called Supernova 1987A (SN 1987A), blazed with the power of 100 million suns for several months following its discovery on Feb. 23, 1987.

Since that first sighting, SN 1987A has continued to fascinate astronomers with its spectacular light show. Located in the nearby Large Magellanic Cloud, it is the nearest supernova explosion observed in hundreds of years and the best opportunity yet for astronomers to study the phases before, during, and after the death of a star.

Zooming in on Supernova 1987A

Video above: The video begins with a nighttime view of the Small and Large Magellanic clouds, satellite galaxies of our Milky Way. It then zooms into a rich star-birth region in the Large Magellanic Cloud. Nestled between mountains of red-colored gas is the odd-looking structure of Supernova 1987A, the remnant of an exploded star that was first observed in February 1987. The site of the supernova is surrounded by a ring of material that is illuminated by a wave of energy from the outburst. Two faint outer rings are also visible. All three rings existed before the explosion as fossil relics of the doomed star’s activity in its final days. Video Credits: NASA, ESA, and G. Bacon (STScI).

To commemorate the 30th anniversary of SN 1987A, new images, time-lapse movies, a data-based animation based on work led by Salvatore Orlando at INAF-Osservatorio Astronomico di Palermo, Italy, and a three-dimensional model are being released. By combining data from NASA's Hubble Space Telescope and Chandra X-ray Observatory, as well as the international Atacama Large Millimeter/submillimeter Array (ALMA), astronomers — and the public — can explore SN 1987A like never before.

Hubble has repeatedly observed SN 1987A since 1990, accumulating hundreds of images, and Chandra began observing SN 1987A shortly after its deployment in 1999. ALMA, a powerful array of 66 antennas, has been gathering high-resolution millimeter and submillimeter data on SN 1987A since its inception.

Hubble Chronicles Brightening of Ring around Supernova 1987A

Video above: This time-lapse video sequence of Hubble Space Telescope images reveals dramatic changes in a ring of material around the exploded star Supernova 1987A. The images, taken from 1994 to 2016, show the effects of a shock wave from the supernova blast smashing into the ring. The ring begins to brighten as the shock wave hits it. The ring is about one light-year across. Video Credits: NASA, ESA, and R. Kirshner (Harvard-Smithsonian Center for Astrophysics and Gordon and Betty Moore Foundation), and P. Challis (Harvard-Smithsonian Center for Astrophysics).

"The 30 years' worth of observations of SN 1987A are important because they provide insight into the last stages of stellar evolution," said Robert Kirshner of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, and the Gordon and Betty Moore Foundation in Palo Alto, California.

The latest data from these powerful telescopes indicate that SN 1987A has passed an important threshold. The supernova shock wave is moving beyond the dense ring of gas produced late in the life of the pre-supernova star when a fast outflow or wind from the star collided with a slower wind generated in an earlier red giant phase of the star's evolution. What lies beyond the ring is poorly known at present, and depends on the details of the evolution of the star when it was a red giant.

"The details of this transition will give astronomers a better understanding of the life of the doomed star, and how it ended," said Kari Frank of Penn State University who led the latest Chandra study of SN 1987A.

Supernovas such as SN 1987A can stir up the surrounding gas and trigger the formation of new stars and planets. The gas from which these stars and planets form will be enriched with elements such as carbon, nitrogen, oxygen and iron, which are the basic components of all known life. These elements are forged inside the pre-supernova star and during the supernova explosion itself, and then dispersed into their host galaxy by expanding supernova remnants. Continued studies of SN 1987A should give unique insight into the early stages of this dispersal.

Image above: These images, taken between 1994 and 2016 by NASA's Hubble Space Telescope, chronicle the brightening of a ring of gas around an exploded star. Image Credits: NASA, ESA, and R. Kirshner (Harvard-Smithsonian Center for Astrophysics and Gordon and Betty Moore Foundation), and P. Challis (Harvard-Smithsonian Center for Astrophysics).

Some highlights from studies involving these telescopes include:

Hubble studies have revealed that the dense ring of gas around the supernova is glowing in optical light, and has a diameter of about a light-year. The ring was there at least 20,000 years before the star exploded. A flash of ultraviolet light from the explosion energized the gas in the ring, making it glow for decades.

The central structure visible inside the ring in the Hubble image has now grown to roughly half a light-year across. Most noticeable are two blobs of debris in the center of the supernova remnant racing away from each other at roughly 20 million miles an hour.

From 1999 until 2013, Chandra data showed an expanding ring of X-ray emission that had been steadily getting brighter. The blast wave from the original explosion has been bursting through and heating the ring of gas surrounding the supernova, producing X-ray emission.

In the past few years, the ring has stopped getting brighter in X-rays. From about February 2013 until the last Chandra observation analyzed in September 2015 the total amount of low-energy X-rays has remained constant. Also, the bottom left part of the ring has started to fade. These changes provide evidence that the explosion's blast wave has moved beyond the ring into a region with less dense gas. This represents the end of an era for SN 1987A.

Beginning in 2012, astronomers used ALMA to observe the glowing remains of the supernova, studying how the remnant is actually forging vast amounts of new dust from the new elements created in the progenitor star. A portion of this dust will make its way into interstellar space and may become the building blocks of future stars and planets in another system.

These observations also suggest that dust in the early universe likely formed from similar supernova explosions.

Astronomers also are still looking for evidence of a black hole or a neutron star left behind by the blast. They observed a flash of neutrinos from the star just as it erupted. This detection makes astronomers quite certain a compact object formed as the center of the star collapsed — either a neutron star or a black hole — but no telescope has uncovered any evidence for one yet.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington.

ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), NSC and ASIAA (Taiwan), and KASI (Republic of South Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ.

Video above: The unpiloted Russian ISS Progress 66 cargo craft automatically docked to the International Space Station Feb. 24, completing a two-day journey to deliver almost three tons of food, fuel and supplies for the residents of the complex. The Progress linked up to the Pirs Docking Compartment on the Russian segment of the complex two days after its launch on a Soyuz booster from the Baikonur Cosmodrome in Kazakhstan. It was the first launch of a Progress resupply craft to the station since a launch failure last Dec. 1 resulted in the loss of the ISS Progress 65 ship.

The map is projected here at a scale of 25 centimeters (9.8 inches) per pixel. [The original image scale is 26.7 centimeters (10.5 inches) per pixel (with 1 x 1 binning); objects on the order of 80 centimeters (31.5 inches) across are resolved.] North is up.

The International Astronomical Union (IAU) – the internationally recognized authority for naming celestial bodies and their surface features – has approved themes submitted by NASA’s New Horizons team for naming surface features on Pluto and its moons.

Image above: This composite of enhanced color images of Pluto (lower right) and Charon (upper left), taken by NASA's New Horizons spacecraft on July 14, 2015, highlights the wide range of surface features on the small worlds. Working with the New Horizons mission team, the International Astronomical Union (IAU) has approved the themes to be used for naming the surface features on Pluto and its moons. Image Credits: NASA/JHUAPL/SwRI.

In 2015, NASA’s New Horizons spacecraft delivered the first close-up views of Pluto and its five moons – amazing images of distant and surprisingly complex worlds, showing a vast nitrogen glacier as well as ice mountains, canyons, cliffs, craters and more. The IAU’s action clears the way for the mission team to propose formal names for dozens of individual surface features.

“Imagine the thrill of seeing your name suggestion on a future map of Pluto and its moons,” said Jim Green, director of NASA’s Planetary Science Division in Washington. “Months after the Pluto flyby, the New Horizons mission continues to engage and inspire.”

Working with the New Horizons team, the IAU has agreed to naming themes (listed below) for Pluto, its largest moon, Charon, and its four smaller moons—Styx, Nix, Kerberos, and Hydra. Some of these themes build on the connection between the Roman god Pluto and the mythology of the underworld. Other themes celebrate the human spirit of exploration.

Pluto

● Gods, goddesses and other beings associated with the underworld from mythology, folklore and literature● Names for the underworld and for underworld locales from mythology, folklore and literature● Heroes and other explorers of the underworld● Scientists and engineers associated with Pluto and the Kuiper Belt● Pioneering space missions and spacecraft● Historic pioneers who crossed new horizons in the exploration of the Earth, sea and sky

Charon

● Destinations and milestones of fictional space and other exploration● Fictional and mythological vessels of space and other exploration● Fictional and mythological voyagers, travelers and explorers● Authors and artists associated with space exploration, especially Pluto and the Kuiper Belt

As a precursor to the naming process now underway between the IAU and New Horizons, in early 2015 the IAU endorsed the NASA-New Horizons led “Our Pluto” naming campaign, which allowed the public to participate in the exploration of Pluto by proposing names for surface features that were still awaiting discovery. That campaign was a partnership between the mission, NASA and the SETI Institute, of Mountain View, California.

“I’m very happy with both the process and partnership that New Horizons and the IAU undertook that led to wonderful, inspiring, and engaging naming themes for surface features on Pluto and its moons,” said Alan Stern, New Horizons principal investigator from Southwest Research Institute, Boulder, Colorado. “We look forward to the next step—submitting actual feature names for approval.”

The SpaceX Dragon cargo spacecraft was berthed to the Harmony module of the International Space Station at 8:12 a.m. EST. The hatch between the newly arrived spacecraft and the Harmony module of the space station is scheduled to be opened this afternoon. The capsule will spend about four weeks attached to the station.

Image above: he SpaceX Dragon was successfully installed to the Harmony module a few hours after it was captured with the Canadarm2. Image Credit: NASA.

U.S. Commercial Cargo Craft Arrives at the International Space Station

With Dragon now berthed to station, the Expedition 50 crew will focus on its next cargo delivery, which is scheduled to arrive in less than 24 hours. The Russian Progress 66 was launched on Wednesday, Feb. 22 from Kazakhstan. It will arrive on station Friday morning for an automated docking at 3:34 a.m. EST and remain on the station until June. NASA Television will cover its arrival beginning at 2:45 a.m. EST.: http://www.nasa.gov/live.

Astronauts Capture Dragon with Robotic Arm

Image above: The SpaceX Dragon is pictured in the grips of the Canadarm2 shortly after its capture by astronauts Shane Kimbrough and Thomas Pesquet. Image Credit: NASA TV.

While the International Space Station was traveling about 250 statute miles over the west coast of Australia, Expedition 50 Commander Shane Kimbrough of NASA and Flight Engineer Thomas Pesquet of ESA (European Space Agency) captured Dragon a few minutes ahead of schedule at 5:44 a.m. EST.

mercredi 22 février 2017

NASA and SpaceX flight controllers in Houston and Hawthorne, California are reworking plans for the arrival Thursday of the SpaceX Dragon cargo craft after its rendezvous to the International Space Station was aborted early Wednesday morning. The Dragon’s computers received an incorrect navigational update, triggering an automatic wave off.

Dragon was sent on a “racetrack” trajectory in front of, above and behind the station for a second rendezvous attempt Thursday. Dragon is in excellent shape and neither the crew nor the station were in any danger. NASA TV will cover its second rendezvous attempt Thursday beginning at 4 a.m. EST.: http://www.nasa.gov/live

Image above: The SpaceX Dragon was pictured from a video camera as it approached the space station Wednesday morning. Image Credit: NASA.

Expedition 50 commander Shane Kimbrough and Thomas Pesquet will be back in the cupola Thursday waiting to capture Dragon at around 6 a.m. Flight Engineer Peggy Whitson will be assisting the duo monitoring Dragon’s arrival and its systems.

A few hours before Dragon aborted its rendezvous, Russia launched its Progress 66 (66P) resupply ship from Kazakhstan on a two-day trip to the station’s Pirs docking compartment. The 66P is carrying nearly three tons of food, fuel and supplies to the six-member Expedition 50 crew. It will arrive Friday for an automated docking at 3:34 a.m. and stay at the station until June. NASA TV will also cover its arrival starting at 2:45 a.m.

For more than a decade, CubeSats, or small satellites, have paved the way to low-Earth orbit for commercial companies, educational institutions, and non-profit organizations. These small satellites offer opportunities to conduct scientific investigations and technology demonstrations in space in such a way that is cost-effective, timely and relatively easy to accomplish.

Animation above: CubeSats are deployed into orbit from the NanoRacks module aboard the International Space Station. Animation Credit: NASA.

The cube-shaped satellites measure about four inches on each side, have a volume of about one quart and weigh less than three pounds per unit (U). CubeSats can also be combined and built to standard dimensions of 1U, 2U, 3U, 6U, etc. for configurations about the size of a loaf of bread, large shoebox, microwave, and more.

These small sats are used by scientists and researchers from all over the world as a way to take bold steps when it comes to space science and exploration. Their small size makes it possible to rapidly build and test, making CubeSats an ideal and affordable way to explore new technologies and ideas.

Commercial Entities

CubeSat technology is used by many organizations outside of NASA to explore low-Earth orbit and the effects of microgravity. Together with NASA, companies like Orbital ATK, SpaceX, and NanoRacks give commercial companies the opportunity to fly their CubeSats as auxiliary payloads on cargo resupply missions to the International Space Station. In addition, Rocket Lab and Virgin Galactic will soon provide dedicated CubeSat launches from the new Venture Class Launch Services. CubeSats may be deployed directly from the rocket, from a spacecraft, or from the station itself depending on the mission.

Planet Labs have developed a series of CubeSats to be launched across several expeditions, many of which have been deployed from the International Space Station via the NanoRacks CubeSat Deployer. These Earth-imaging satellites will provide imagery to a variety of users as they focus on highly populated and agricultural areas to study urbanization and deforestation. The images will be used to improve natural disaster relief and crop yields in developing nations.

Image above: CubeSats STMSat-1, CADRE and MinXSS are deployed from the International Space Station during Expedition 47. Image Credit: NASA.

Each proposed investigation must demonstrate a benefit to NASA by addressing aspects of science, exploration, technology development, education or operations relevant to NASA’s strategic goals. This initiative provides NASA a mechanism for low-cost technology development and scientific research to help bridge strategic knowledge gaps and accelerate flight-qualified technology.

Since its inception CSLI has selected 152 CubeSat missions from 68 universities and in 2015, NASA launched first CubeSat designed and built by elementary students. The recent eighth round of CubeSat selections will include 34 small satellites from 19 states and the District of Columbia to fly as auxiliary payloads aboard missions planned to launch in 2018, 2019 and 2020

Benefits on Earth

CubeSat missions benefit Earth in varying ways. From Earth imaging satellites that help meteorologists to predict storm strengths and direction, to satellites that focus on technology demonstrations to help define what materials and processes yield the most useful resources and function best in a microgravity environment, the variety of science enabled by CubeSats results in diverse benefits and opportunities for discovery.

Image above: PhoneSat 2.5, launched in April 2014, was developed by NASA Ames Research Center to use commercial smartphone technology for low-cost development of basic spacecraft capabilities. Image Credit: NASA.

“You never know what they’re going to discover or find,” said Susan Mayo, National Lab and Education Specialist for the International Space Station Program Science Office. “What better systems will emerge for Earth imaging? Are we going to develop a better system for doing something? You never know what long-term impact can come out of it. That’s what this is all about - how is it going to benefit life on Earth in the end?”

CubeSats are bringing dreams of spaceflight, discovery and science closer to home than ever. For more information about science and research aboard the station, visit ISS Research and Technology.

Temperate Earth-sized Worlds Found in Extraordinarily Rich Planetary System

Artist’s impression of the TRAPPIST-1 planetary system

Astronomers have found a system of seven Earth-sized planets just 40 light-years away. Using ground and space telescopes, including ESO’s Very Large Telescope, the planets were all detected as they passed in front of their parent star, the ultracool dwarf star known as TRAPPIST-1. According to the paper appearing today in the journal Nature, three of the planets lie in the habitable zone and could harbour oceans of water on their surfaces, increasing the possibility that the star system could play host to life. This system has both the largest number of Earth-sized planets yet found and the largest number of worlds that could support liquid water on their surfaces.

Image above: Comparison of the TRAPPIST-1 system with the inner Solar System and the Galilean Moons of Jupiter.

Astronomers using the TRAPPIST–South telescope at ESO’s La Silla Observatory, the Very Large Telescope (VLT) at Paranal and the NASA Spitzer Space Telescope, as well as other telescopes around the world [1], have now confirmed the existence of at least seven small planets orbiting the cool red dwarf star TRAPPIST-1 [2]. All the planets, labelled TRAPPIST-1b, c, d, e, f, g and h in order of increasing distance from their parent star, have sizes similar to Earth [3].

Image above: Comparison of the TRAPPIST-1 system with the inner Solar System and the Galilean Moons of Jupiter.

Dips in the star’s light output caused by each of the seven planets passing in front of it — events known as transits — allowed the astronomers to infer information about their sizes, compositions and orbits [4]. They found that at least the inner six planets are comparable in both size and temperature to the Earth.

Comparison of the sizes of the TRAPPIST-1 planets with Solar System bodies

Lead author Michaël Gillon of the STAR Institute at the University of Liège in Belgium is delighted by the findings: “This is an amazing planetary system — not only because we have found so many planets, but because they are all surprisingly similar in size to the Earth!”

With just 8% the mass of the Sun, TRAPPIST-1 is very small in stellar terms — only marginally bigger than the planet Jupiter — and though nearby in the constellation Aquarius (The Water Carrier), it appears very dim. Astronomers expected that such dwarf stars might host many Earth-sized planets in tight orbits, making them promising targets in the hunt for extraterrestrial life, but TRAPPIST-1 is the first such system to be found.

The orbits of the seven planets around TRAPPIST-1

Co-author Amaury Triaud expands: “The energy output from dwarf stars like TRAPPIST-1 is much weaker than that of our Sun. Planets would need to be in far closer orbits than we see in the Solar System if there is to be surface water. Fortunately, it seems that this kind of compact configuration is just what we see around TRAPPIST-1!”

VLT observations of the light curve of TRAPPIST-1 during the triple transit of 11 December 2015

The team determined that all the planets in the system are similar in size to Earth and Venus in the Solar System, or slightly smaller. The density measurements suggest that at least the innermost six are probably rocky in composition.

Light curves of the seven TRAPPIST-1 planets as they transit

The planetary orbits are not much larger than that of Jupiter’s Galilean moon system, and much smaller than the orbit of Mercury in the Solar System. However, TRAPPIST-1’s small size and low temperature mean that the energy input to its planets is similar to that received by the inner planets in our Solar System; TRAPPIST-1c, d and f receive similar amounts of energy to Venus, Earth and Mars, respectively.

Comparison of the TRAPPIST-1 system and the inner Solar System

All seven planets discovered in the system could potentially have liquid water on their surfaces, though their orbital distances make some of them more likely candidates than others. Climate models suggest the innermost planets, TRAPPIST-1b, c and d, are probably too hot to support liquid water, except maybe on a small fraction of their surfaces. The orbital distance of the system’s outermost planet, TRAPPIST-1h, is unconfirmed, though it is likely to be too distant and cold to harbour liquid water — assuming no alternative heating processes are occurring [5]. TRAPPIST-1e, f, and g, however, represent the holy grail for planet-hunting astronomers, as they orbit in the star’s habitable zone and could host oceans of surface water [6].

The ultracool dwarf star TRAPPIST-1 in the constellation of Aquarius

These new discoveries make the TRAPPIST-1 system a very important target for future study. The NASA/ESA Hubble Space Telescope is already being used to search for atmospheres around the planets and team member Emmanuël Jehin is excited about the future possibilities: “With the upcoming generation of telescopes, such as ESO’s European Extremely Large Telescope and the NASA/ESA/CSA James Webb Space Telescope, we will soon be able to search for water and perhaps even evidence of life on these worlds.”

Artist's illustrations of planets in TRAPPIST-1 system and Solar System’s rocky planets

Notes:

[1] As well as the NASA Spitzer Space Telescope, the team used many ground-based facilities: TRAPPIST–South at ESO’s La Silla Observatory in Chile, HAWK-I on ESO’s Very Large Telescope in Chile, TRAPPIST–North in Morocco, the 3.8-metre UKIRT in Hawaii, the 2-metre Liverpool and 4-metre William Herschel telescopes at La Palma in the Canary Islands, and the 1-metre SAAO telescope in South Africa.

Artist’s impression of the TRAPPIST-1 system

[2] TRAPPIST–South (the TRAnsiting Planets and PlanetesImals Small Telescope–South) is a Belgian 0.6-metre robotic telescope operated from the University of Liège and based at ESO’s La Silla Observatory in Chile. It spends much of its time monitoring the light from around 60 of the nearest ultracool dwarf stars and brown dwarfs (“stars” which are not quite massive enough to initiate sustained nuclear fusion in their cores), looking for evidence of planetary transits. TRAPPIST–South, along with its twin TRAPPIST–North, are the forerunners to the SPECULOOS system, which is currently being installed at ESO’s Paranal Observatory.

Comparing the TRAPPIST-1 planets

[3] In early 2016, a team of astronomers, also led by Michaël Gillon announced the discovery of three planets orbiting TRAPPIST-1. They intensified their follow-up observations of the system mainly because of a remarkable triple transit that they observed with the HAWK-I instrument on the VLT. This transit showed clearly that at least one other unknown planet was orbiting the star. And that historic light curve shows for the first time three temperate Earth-sized planets, two of them in the habitable zone, passing in front of their star at the same time!

Seven planets orbiting the ultracool dwarf star TRAPPIST-1

[4] This is one of the main methods that astronomers use to identify the presence of a planet around a star. They look at the light coming from the star to see if some of the light is blocked as the planet passes in front of its host star on the line of sight to Earth — it transits the star, as astronomers say. As the planet orbits around its star, we expect to see regular small dips in the light coming from the star as the planet moves in front of it.

Animation of the planets orbiting TRAPPIST-1

[5] Such processes could include tidal heating, whereby the gravitational pull of TRAPPIST-1 causes the planet to repeatedly deform, leading to inner frictional forces and the generation of heat. This process drives the active volcanism on Jupiter's moon Io. If TRAPPIST-1h has also retained a primordial hydrogen-rich atmosphere, the rate of heat loss could be very low.

Fly-through of the TRAPPIST-1 planetary system

[6] This discovery also represents the largest known chain of exoplanets orbiting in near-resonance with each other. The astronomers carefully measured how long it takes for each planet in the system to complete one orbit around TRAPPIST-1 — known as the revolution period — and then calculated the ratio of each planet’s period and that of its next more distant neighbour. The innermost six TRAPPIST-1 planets have period ratios with their neighbours that are very close to simple ratios, such as 5:3 or 3:2. This means that the planets most likely formed together further from their star, and have since moved inwards into their current configuration. If so, they could be low-density and volatile-rich worlds, suggesting an icy surface and/or an atmosphere.

A trip to TRAPPIST-1 and its seven planets

More information:

This research was presented in a paper entitled “Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1”, by M. Gillon et al., to appear in the journal Nature.

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

The unpiloted Russian Progress 66 launched at 12:58 a.m. Wednesday (11:58 a.m. Baikonur time) from the Baikonur Cosmodrome in Kazakhstan. It is now orbiting the planet on course for the International Space Station.

Russian Cargo Craft Sets Sail for the International Space Station

The vehicle will deliver almost three tons of food, fuel and supplies to the Expedition 50 crew.

The spacecraft is set to dock to the Pirs docking compartment at 3:34 a.m. Friday, Feb. 24. NASA TV coverage of rendezvous and docking will begin at 2:45 a.m. Progress 66 will remain docked at the station for almost four months before departing in June for its deorbit into Earth’s atmosphere.

This was the first launch of a Progress cargo ship from Baikonur since the Progress 65 supply craft was lost Dec. 1, 2016.

The SpaceX Dragon cargo spacecraft waved off its planned rendezvous with the International Space Station at 3:25 a.m. EST. Dragon’s onboard computers triggered the abort after recognizing an incorrect value in navigational data about the location of Dragon relative to the space station. Flight controllers immediately began planning for a second rendezvous attempt on Thursday, Feb. 23.

The spacecraft is in excellent shape with no issues, and the crew aboard the space station is safe. The next rendezvous attempt is targeted for Thursday morning. NASA TV coverage will begin at 4 a.m. with grapple expected around 6 a.m. Installation coverage will begin at 8 a.m. Watch live on NASA TV and online at: http://www.nasa.gov/live.